前几天简单对C和C++中的创建多线程的函数进行了测试,这篇随笔就简单介绍一下创建线程的相关函数。
C中三个创建线程函数:pthread_create()、_beginthread()、CreateThread()
三个关闭线程函数:pthread_exit()、_endthread()、ExitThread()
头文件分别是:pthread.h、process.h、processthreadsapi.h
pthread_create()函数原型:
int pthread_create(pthread_t *tidp,
const pthread_attr_t *attr,
(void*)(*start_rtn)(void*),
void *arg);
_beginthread()函数原型:
uintptr_t _beginthread(void( *start_address )( void * ),
unsignedstack_size,void *arglist);
_beginthread()函数是调用CreateThread()函数来实现的,但多了一些功能,是C标准库中提供的函数。而CreateThread()函数创建一个线程在调用进程的虚拟地址空间内执行,是操作系统中的函数。可参考解释:http://bbs.csdn.net/topics/21693。
CreateThread()函数原型:
HANDLE WINAPI CreateThread(
_In_opt_ LPSECURITY_ATTRIBUTES lpThreadAttributes,
_In_ SIZE_T dwStackSize,
_In_ LPTHREAD_START_ROUTINE lpStartAddress,
_In_opt_ LPVOID lpParameter,
_In_ DWORD dwCreationFlags,
_Out_opt_ LPDWORD lpThreadId
);
pthread_exit()函数原型:
void pthread_exit(void *retval);
_endthread()函数原型:
void _endthread( void );
void _endthreadex(
unsigned retval
);
ExitThread()函数原型:
VOID WINAPI ExitThread(
_In_ DWORD dwExitCode
);
貌似要使用pthread_exit();需要安全释放,否则会出现内存泄露:pthread_exit()
下面测试一下各个函数:
pthread.h:
#include <stdio.h> #include <stdlib.h> #include <pthread.h> #define MAXTHREADS 5 void* Run(void* args) { printf("%d:Hello World! ", *((int*)args)); pthread_exit(NULL); return NULL; } int main() { pthread_t tid[MAXTHREADS]; pthread_attr_t attr; void*status; int ret; pthread_attr_init(&attr);//初始化attr pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);//设置获得attr的线程为可连接的:PTHREAD_CREATE_JOINABLE 原型为 0 for(int i = 0; i < MAXTHREADS; i++) { if((ret = pthread_create(&tid[i], &attr, Run, (void*)&i)) != 0)//获得attr,则线程可连接 { puts("Pthread_Create error!"); exit(1); } pthread_join(tid[i], &status);//等待线程结束,结束的线程便不能再被连接 } pthread_attr_destroy(&attr);//销毁attr资源 return 0; }
pthread_join等待其他线程结束后再连接能连接的函数,已经结束的线程便不能再被连接。所以输出结果可看到是按顺序执行的。感觉就是加上了互斥锁,不知道理解对不对?
process.h:
#include <stdio.h> #include <stdlib.h> #include <process.h> #define MAXTHREAD 5 void run(void*i) { printf("%d:Hello world! ", *((int*)i)); } int main() { for(int i = 0; i < MAXTHREAD; i++) { _beginthread(&run, 0, (void*)&i); } _endthread(); return 0; }
消除了类型强转的警告,但程序无法正常退出,有时也无法正常进行。
--------------------update 2018-02-24 16:09:01---------------------
processthreadsapi.h:
#include <windows.h> #define MAXTHREAD 5 HANDLE ghMutex; DWORD WINAPI Run_Process(LPVOID p) { WaitForSingleObject(ghMutex, INFINITE); try { TCHAR s = *((int*)p)+'0'; MessageBoxA(NULL, TEXT("Hello world!"), TEXT(&s), MB_ICONWARNING | MB_OK); ReleaseMutex(ghMutex); } catch(...) { if (! ReleaseMutex(ghMutex)) MessageBoxA(NULL, TEXT("ReleaseMutex Error!"), TEXT("ERROR"), MB_ICONERROR | MB_OK); } return GetLastError(); } int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE HPrevInstance, PSTR szCmdLine, int iCmdShow) { DWORD dwThreadIdArray[MAXTHREAD]; HANDLE hThreadArray[MAXTHREAD]; if((ghMutex = CreateMutex(NULL, FALSE, NULL)) == NULL) { ExitProcess(1); } for(int i = 0; i < MAXTHREAD; i++) { hThreadArray[i] = CreateThread( NULL, 0, Run_Process, (LPVOID)&i, 0, &dwThreadIdArray[i]); if (hThreadArray[i] == NULL) { ExitProcess(3); } } WaitForMultipleObjects(MAXTHREAD, hThreadArray, TRUE, INFINITE); for(int i = 0; i < MAXTHREAD; i++) { CloseHandle(hThreadArray[i]); } CloseHandle(ghMutex); return 0; }
参考我的这篇随笔:
http://www.cnblogs.com/darkchii/p/8447863.html
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参考资料:
http://www.man7.org/linux/man-pages/man3/pthread_exit.3.html http://www.man7.org/linux/man-pages/man3/pthread_create.3.html http://www.cppblog.com/prayer/archive/2012/04/23/172427.html https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659(v=vs.85).aspx https://msdn.microsoft.com/en-us/library/windows/desktop/ms682453(v=vs.85).aspx https://msdn.microsoft.com/zh-cn/library/hw264s73.aspx